Mercury switch thermostat



June s, 1933. QJ. wARNKE 1,913,135

MERCURY 'SWITCH THERMOSTAT Filed Feb. l, 1932 UIMHHII".

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` time than is now obtainable with l Patented June 6, 1933 UNITED STATES PATENT oFElcE cam. .1. wamzxr., or Emrnaar, ranura, Assrenon. or ons-HALF ro mams c. commu', or annum.. INDIANA.

IEBCUBY THEBIOSTAT application ma mmm-y 1, ina. smal la. ssogooa.

My invention relates to a thermostat having thermometric characteristics for the remote control of various types of apparatus, such -as oil burners, furnaces, mechanical refrigerators andthe like, and more particularly to' one incorporatmg a mercury switch structure which is featured by a more eicient operation over a longer period of thermostats of standard construction. A

One object of my invention is to devise a thermostat of the .character indicated in which the electrical circuit is` completed through the switch by a member located within the switch container and adjustably held in any desired position by an externally located, magnetic member.

A'further object is the provision yof a mer- `cury switch thermostat having a thermometer tube in which contact ofthe mercury with the adjustable member for anyxposition j.

thereof is4 determined by the position of the lso mercury. in the tube in response to external temperature conditions, the adjustable member having a part extending within the t'ube for contact with the mercury. v

A further object is to embody in a mercury switch thermostat having a thermometer structure an arrangement for positively determining the initialI or zero position of the mercury in the capillary tube and to vary such position as desired, thus roviding in conjunction with the adjustab e member' a further means for varying the operating characteristicsA of the instrument in respect of the temperature at which it functions and the time required at any given temperature for the mercury to rise in the tube until it contacts with the adjustable member.

A further object is to provide a thermostat of the type set forth for use under tem erature conditions in excess of those to whlch a mercury thermometer is normally exposed through filling the container ofthe yswitch with a gas at a suilicient pressure to raise the boiling point of the mercury.

My invention is primarily intended to pro.- vide an improved type of mercury switch for thermostatic purposes,` such as the remote temperature control of various kinds of apparatus, including oil burners, furnaces, mechanical refrigerators and the, like. portion 'of the switch com rises a thermometer tube which maybe ca ibrated according to any temperature scale and within the capillary tube of which is mounted an adjustable part which is contacted by the mercury as it rises in the tube, or losesl contact therewith as it falls, by reason of changes in the temperature to w ich the instrument is exposed. Preferably, the adjustable part is moved and held in any adjusted position by a magnet of some form, whether of the permanent or of theelectro-xnagnet t pe, and it is also contemplated that an additional device One l may be incorporated in the thermostat for 'positively determining the initial or zero sition of the mercury in the capillary tu. The association of the two indicated arrangements provides for a wide range of adjustment of the thermostat and s o renders it adaptable for use under a wide variety of conditions. p l

These and further objects of my invention will be set forth1inthe following specification, reference being had to the accompanyin drawing, and the novel means by which definitely" said objects are eifectuated will be pointed out in the claims.

In the drawin Figure 1 is an e evation, partly in section of p my improved thermostat, as it is viewed from the scale reading side thereof.

Fig. 2 is a sectional elevation of the thermostat taken generally along the line 2 2 in Fi 5looking in the direction of thearrows.

ig. 3 isa section along the line 3-3 in Fi 1', looking in the direction of the arrows,

an showing the manner in which the thermometer tube is formed in the mercury switch container.

Fig. 4 is a section along the line 4 4 in Fig. 1, looking in the direction of the arrows, and showing the relation of the pole portions of the magnet' to the switch container.

Fig. 5 lis a section along the line 5 5 in Fig. 2, looking in the direction of the arrows, and showing the relation to, and the manner of guiding, the adjustable part within the switch container.

Fig. 6 is a sectional elevation of the lower portion of the thermostat, corresponding generally to the lower portion of Fig. 2, and showing a modified construction whereby the initial level of one of the mercury pools may be adj usted.

Fig. 7 is an enlarged section along the line 7-7 in Fig. 6, looking in the direction of the arrows, f'and showing the mechanism for varying the mercury level.

Referring to Figs. 1 to 5, inclusive, the numeral 10 designates the container of the mercury switch portion of the thermostat, which is generally elongated in shape and which may be composed of any of the glasses now used for mercury switches, the precise nature of the glass forming no part of my invention. I

The container 10is provided with a lower end wall 11 and is pinch-sealed at the opposite end, as at 12, in the customary manner. A wall 13 divides the interior of the container 10 into chambers 14 and 15, lower and upper, respectively, as the thermostat is viewed in Fig. 3, and said chambers receive, respectively, pools of mercury 16 and 17, said pools having a predetermined depth, as determined by operative conditions. A portion 18 of the wall 13 defines with the adjacent wall of the container 10, a capillary tube 19 and said wall portion 18 is preferably parti-cylindrical in cross section, as shown clearly in Fig. 5, for a purpose hereinafter explained. v The exterior ofthe portion of the container wall 10 adjacent the capillary tube 19 may be calibrated according to any well-known temperature scale, or in any other manner, as iFndicated generally by the numeral 20 in ig. 1. A

Extending'through the endt wall 11 arey lead-in wires 21 and 22, the material composing these wires being that which is usually employed for a like purpose, such as dumet wire and otherwise of similar characteristics, and the character of the seal between these lead-in wires and the glass container being such as to prevent leakage at the indicated points and said conductors being also preferably arranged, as regards their composing materials, that they are characterized by substantially the same coefficient `of thermal expansion as the material forming the container 10. An electrode 23 is suitably connected to the lead-in wire 21 within the lower chamber 14, while the leadin wire 22 extends upwardly through a glass insulating sleeve 24 which is fused at one end to the wall 11 and at the opposite end to a portion 25 of the wall 13, so that the lead-in wire 22 is completely shielded from contact with the mercury pool 16. The wire 22 extends through the wall portion 25 and within the upper chamber 15 has attached thereto an electrode 26 which is at all times completely covered by the mercury pool 17, just as the electrode 23 i is always covered by Jthe mercury pool 16. The precise materials of which said electrodes are composed form no part of the present invention, since standard practice may be adopted in this respect, although it is comtemplated that in any case the material selected will be such as to offer resistance to the erosive effect of the electric arc.

A sleeve 27, having generally a crescentlike cross section, as shown in Fig. 5, is mounted within the upper chamber 15. The skirt portions 28 and 29, defined generally by the large and small radii of the crescent lformation, are joined at their upper ends by the top portion 30, while the lower ends of these portions are always immersed in the mercury pool 17. The skirt portion 29 closely fits the parti-cylindrical shape of the wall portion 18 and is guided thereby in its vertical movement, while also being held against separation therefrom in lateral directions. A portion of the top 30 project-s above the upper endof the capillary tube 19 and carries the fine wire 31 which projects downwardly through an aperture 32 provided in the wall 13 and also downwardly into the capillary tube 19. The sleeve 27 is preferably formed of a material having a relatively high magnetic permeability, such as nickel iron or equivalent material, or alloys formed of such materials, while the wire 31 may be composed of a material similar 'to that comprising the electrodes 23 and 26, for, as will be presently shown, the electrical circ-uit between the electrodes 23 and 26 is broken at the lower end of the wire 31.

- It will be understood that. prior to the pinch-sealing of the end 12, the interior of the container 10 will be exhausted. including the chambers 14 and 15. in accordance with standard practice and afterwards filled with one of the gases which are usually emploved for the purpose of substantially suppressing the electric arc whichl tends to form when a circuit ismade or broken in the switch. Many favorable results flow from the use of suchgases, such as a marked improvement in the heat conducting characteristics with in the container, protecting the wire 31 from deterioration arising from ionization or from whatever cause, arresting the wetting or amalgamation ot the Wire 31 by the mercury, and

of keeping the wire surface clean at all times.

In order to shift and maintain the sleeve 27 in any adjusted position. it is contemplated that a magnet 33 will be employed, said magnet having pole pieces 34 and 35 which closely fit the exterior of the container 10 and are mounted to slide freely therealong.

In the drawing, the magnet 33 is denoted as being of a common bar type, although it will be understood that any electro-magnet mayv he employed, the magnet 33 being intended to illustrate generically any magnetic means for securing the desired shiftingl of the sleeve .In the use of my improved thermostat, the

lead-in wires 21 and 22 will be connected to some :form of'electrical circuit Whosel operation it is desired to control by the thermostat. The precise nature of this external circuit forms no part of the present invention, but

for purpose of illustration, it may be briefly stated that they find their counterpart in any of the present oil burner installations, or mechanical refrigerators, furnaces, and apparatus generally where some form of temperature control is desired.

Assuming that the sleeve 27 has been raised until the lower end of the wire 31 is clear of the mercury' in the tube 19 and has been placed in a position determined by solne convenient reading of the scale 20, and, further, that the thermostat is being employed in connection with a circuit wherein a rise of temperature will require the happeningof a certain condition in the external circuit, then with the sleeve 27 occupying the indicated position, it will be obvious that an electrical current cannot flow between the electrodes 23 and 26 for the circuit is broken within the switch by reason of the separation of the wire 31 from the mercury pool 16. However. as the external temperature continues to ri se, the mercury will rise in the capillary tube 19, in accordance with well-known principles, until it finally touches the lower end of the wire 31, whereupon the circuit willI be completed between the electrodes 23 and 26, thus affecting the operation of the apparatus with which the thermostat is connected.

The indicated circuit will be maintained so long as the external temperature does not fall below that corresponding with the lower end of the wire 31 and will beuna'ected by a continuing rise in temperature above the minimum indicated. When the temperature does fall, however, a point will be eventually Ireached when the mercury in the capillary tube will fall below the lower end of the wire 31, where-upon the circuit will be broken between the electrodes of the thermostat.

The provision of the magnetic sleeve 27 and the magnet 33 affords a convenient method of placing the sleeve 27 in any desired position, while the length ofthe wire 31 within the capillary tube 19 provides for a convenient time lag in the o ration of the thermostat, as may be desira le under certain conditions. For example, after the met'- cury has once contacted with the lower end of the wire 31, an additional rise of the external temperature does not affect the operation of the thermostat, nor does an ensuing drop in the temperature, following arise above that indicated by the lower end of the wire 31, affect the instrument until the temperature drop is suflicient to cause a separation of the wire and mercury.l j

ally to the'container 10, is provided at its lower end with ametallic diaphragm 37 in place of the glass, end wall 11. The diaphragm 37 closes one end of a lower chamber 38, corresponding to the chamber 14 and which is separated from an upper chambery 39 by awall-40. Both chambers are provided with mercury pools in the manner above described and within the mercury pool in the chamber 39 is mounted an electrode 41 which is connected externally of the container by a lead-in wire 42. The diaphragm 37 functions as the electrode for the mercury in the chamber 38 and is connected externally of the thermostat by a wire 43.

The diaphragm 37 is composed of metal which will Hex easily without undergoing crystallization and, in the form of apparatus shown lin the figures under discussion, one end of an adjustingscrew 44 contacts with the underside of the diaphragm 37 and is rotatably mounted in a convenient bracket arm 45. This screw may be composed entirely of an insulating material, or simply the end thereof which contacts with the diaphragm. The screw 44 may carry a pointer 46 which is arranged to sweep over a convenient scale 47 which is calibrated to denote an upward or a lowering movement of the diaphragm 37, corresponding to similar movements of the mercury in the chamber 38.

According to the foregoing arrangement, it will be understood that when the adjusting screw 44is appropriately rotated to impart an upward flexing of the diaphragm 37, the mercury in the chamber 38 will rise in the associated capillary tube, While an opposite condition will be achieved by a contrary movement of the adjusting screw. Hence, it is possible by this mechanism to vary the initial or zero position of the mercury in the capillary tube and, in fact, to place such level above that which it would occupy for any given temperature condition. It is therefore possible with such an adjustment, in conjunction with the above-described adjustment of the sleeve 27, to lessen the time required for the mercury to contact with the wire 31, since it is entirely possible to initially place the mercury meniscus in the capillary tube at some point considerably higher than that corresponding to the external temperature. By appropriately operating the adjusting screw 44 and the magnet 33, the thermostat is capable of being adapted for service under aV plurality of conditions, since it is possible to positively control the two variants in the structure, namely, the sleeve 27 and the level of the mercury meniscus in the capillary tube 19.

While I have shown one set of elements and combinations thereof for efectuating my improved thermostat, it will be understood that the same is intended for purpose of illustration only and in no Wise to restrict the device to the exact forms and structures shown, for many changes may be made therein Without departing from the spirit of my invention.

I claim:

l; A thermostat comprisingv a containerdivided by a Wall into first and second mercury receiving chambers, said Wall forming with said container a thermometer tube communicating With said first chmaber, mercury pools in each chamber, an electrode immersed in the mercury in each of said chambers communicating with an external circuit, and a member contacting with the mercury in said second chamber and having a part extending into said tube, the rise and fall of the mercury in said tube in response to temperature changes determining the circuit condition through the thermostat. n

2. A thermostat comprising a container divided by a Wall into first and second mercury receiving chambers, a thermometer tube communicating with said first chamber, mercury pools in each chamber, an electrode immersed in the mercury in each of said chambers communicating with an external circuit, and a member contacting with the mercury in said second chamber and having a part extending; into said tube, the rise and fall of the mercury in said tube in response to temperature changes determining the circuit condition through the thermostat.

3. A thermostat comprising a container divided by a Wall into first and second mercury receiving chambers, a thermometer tube communicating with said first chamber, mercury pools in each chamber, an electrode immersed in the mercury in each of Said chambers connected with an external circuit, and an adjustable .member contacting with the mercury in said second chamber and having a part extending'into said tube,`the rise and fall of the mercury in said tube in response to temperature changesdetermining the circuit condition through the thermostat.

4. A thermostat comprising a container divided by a Wall into first and second mercury receiving chambers, a thermometer tube communicating with said first chamber, mercury pools in each chamber, an electrode immersed in the mercury in each of said chambers connected with an external circuit, an adjustable member contacting with the mercury in said second chamber and having a part extending into said tube, the rise and fall of the mercury insaid tube in response to temperature changes determining the circuit condition through the thermostat, and a part externally of the container for adjusting said member and for holding the same in adjusted position.

5. A thermostat comprising a container divided by a wall into first and second mercury receiving chambers, a thermometer tube communicating with said first chamber, mercury pools in each chamber, an electrode immersed in the mercury in each of said chambers connected with an external circuit, an adjustable member comprising magnetic material contacting with the mercury in said second chamber and having a part extending into said tube, the rise and fallof the mercury in said tube in response to temperature changes determining the circuit condition through the thermostat, and magnetic means externally of the container for adjusting said member and for holding the same in adjusted position. l

6. A thermostat comprising a container divided by a Wall into first and second mercury receiving chambers, said wall forming'with said container a thermometer tube communicating with said first chamber, mercury pools in each chamber, an electrode immersed in the mercury in each of said chambers connected with an external circuit, and a member slidable on the portions of said wall enclosing said tube for contact with the mercury in said second chamber and having a part extending into said tube, the'rise and fall of the mercury in said tube in response vto temperature changes determining the circuit condition through the thermostat.

7. A thermostat comprising a container divided by a Wall into first and second mercury receiving chambers, a thermometer tube communicating with said first chamber, mercury pools in each chamber, an electrode immersed in the mercury in each of said chambers connected with an external circuit, a member contacting with the mercury in said second chamber and having a part extending into said tube, the rise and fall of the mercury in said tube in response to temperature changes determining the circuit condition throu h the thermostat, and means for varying the zero position of the mercury meniscus in said tube.r

8:' A` thermostat comprising a container closed at one end by a diaphragm and divided by a Wall into first and second mercury receiving chambers, mercury pools in each chamber, means for connecting said pools to an external circuit, a thermometer tube communicating with said first chamber, a member contacting with the mercury in said second chamber and having a part extending into said tube, the rise and fall of the mercury in said tube in response to temperature changes determining the circuit condition through the thermostat, and means for flexing said diaphragm to vary the zero position of the mercury meniscus in said tube.

closed at one end b a diphragm and divided by a wall into rst an second mercury receiving chambers, mercury pools in each chamber, an electrode located 1n the pool in said second chamber and said diaphragm acting as electrode for said first chamber, means for connecting said electrode and diaphragm to an external circuit, 4a thermometer tube communicating with said first chamber, a member contacting with the mercury in said second chamber and having a part extending into said tube, the rise and fall of the mercury in said tube in response to temperature changes determining the circuit condition throu h the thermostat, and means 4for Aflexing said diaphragm to vary the zero position of the mercury meniscus in said tube.

10. A thermostat comprising a container divided by a wall into first and second mercury receiving chambers, a thermometer tube communicating with said first chamber, mercury pools in each chamber, an electrode immersed in the mercury in each of said chambers communicating with an external circuit, an adjustable member contacting with` the mercury in said second chamber and having a part extending into said tube, and means for varying the zero position of the mercury meniscus in said tube, the rise and fall of the mercury in said tube in response to temperature changes determining the circuit condition through the thermostat. l

11. A thermostat comprising a container divided by a Wall into first and second mercury receiving chambers, a thermometer tube communicating with said first chamber, mercury pools in each chamber, an electrode immersed in the mercury in each of said chambers connected with an external circuit, an

. adjustable member contacting with the mercury in said second chamber and having a part extending into said tube, a part externally of the container for adjusting said member and for holding the same in adjusted position, and me'ans for varying the zero position of the mercury meniscus in said tube, the rise and fall of the mercury in said tube in response to temperature changes determining the circuit condition through the thermostat.

12. A thermostat comprising an hermetically sealed container internally divided by a wall into first and second mercury-receiving chambers, said wall forming with said container a thermometer tube communicating with said first chamber, mercury pools in each chamber, an electrode immersed in the mercury in each of said chambers,` an inlead wire for each electrode sealed through the wall'of the container and connected with an external circuit, and a member contacting with the mercury in said second chamber and having a part extending into said tube, the rise and fall of the mercu in said tube in response to temperature c anges determining the circuit condition through the thermostat.

13. A thermostat comprising an hermeti-A 4cally sealed, glass tube internally divided by a wall into first and second mercury-receiving chambers, a thermometer tube communieating with said first chamber, mercury pools in each chamber, an electrode immersed in the mercury in each of said chambers, an inlead wire for each electrode sealed throu h thevwall of the glass tube and adapted or connection with an external circuit, an' adjustable member having magnetic character'- istics contacting with the mercury in said second chamber, said member having a portion extending close to the inner wall of said -glass tube and apart extending into said pools in each chamber, an electrode immersedin the mercury in each'of said chambers, an

inlead wire for each electrode sealed through the wall of said glass tube and adapted for connection with an external circuit, and a member having a portion fitting closely around the bulged portion to confine the member to a sliding movement along the bulge, said member being arranged for contact with the mercury in said second chamber and' having a part extending into said thermometer tube, the rise and fall of the mercury in said thermometer tube in response to temperature changes determining the circuit condition through the thermostat.

15. A thermostat comprising an hermetically sealed, tubular glass container internally divided by a wall into first and second mercury-receiving chambers, said wall forming with said container a thermometer tube communicating with said first chamber and lhaving a bulged portion projecting into said second chamber, mercury pools in each chamber, and an electrode immersed in the mercury ineach said chamber, an inlead` wire for each electrode sealed through the wall of said container and adapted for connection with an external circuit, a member having magnetic characteristics provided with a portion fitting closely around said bulge to confine the member to sliding movements along the bulge, said member contacting with the mercury in said second chamber with a portion my name.

CARL J. WARNKE. 

